1. Field of the Invention
The present invention relates to easy-open ends for product containers, particularly, beverage and beer cans. In particular, the present invention provides an improved method for forming easy-open ends, improved tooling, and an improved can end.
2. Prior Art
Many metallic cans for holding beverages or other products are provided with easy-open can ends, wherein a pull tab attached to a tear strip that is defined by a score line in the can end may be pulled to provide an opening in the can end for dispensing the can's contents. For ecological and safety reasons, many regions require that the tear strip and attached pull tab be retained to the can end after opening. In order to meet these requirements, various designs have been suggested by the prior art for ensuring that the tear strip and pull tab do not become separated from the can end. Generally, the pull tab is retained to the can end by means of a rivet. Methods of rivet development utilizing the prior art can be found in U.S. Pat. Nos. 4,465,204 and 4,530,631 both to Kaminski et al., and assigned to the assignee of the instant invention. These patents are incorporated herein by reference as if fully set forth.
In the manufacture of an easy-open can end, a can end shell is first formed from a metal sheet product, preferably an aluminum sheet product. The can end shell is then conveyed to a conversion press. In the typical operation of a conversion press, a can end shell is introduced between an upper tool member and a lower tool member which are in the open, spaced apart position. A press ram advances the upper tool member toward the lower tool member in order to perform any of a variety of tooling operations such as rivet forming, paneling, scoring, embossing, tab securing, and final staking. After performing a tooling operation, the press ram retracts until the upper tool member and lower tool member are once again in the open, spaced apart position. The partially converted shell is transported to the next successive tooling operation until an easy-open can end is completely formed and discharged from the press. As one shell leaves a given tooling operation, another shell is introduced to the vacated operation, thus continuously repeating the entire easy-open can end manufacturing process.
The can end manufacturing industry is continuously striving to reduce costs by developing an increasingly lightweighted can end through both reduced diameter and reduced metal gauge in order to effect enhanced cost savings through the use of less metal in each packaged product. It has been conventional practice to maintain the metal gauge of the can end to a gauge of approximately 0.0108 to 0.0116 inch. The beer and beverage industry believe that is advantageous to provide an enlarged tear strip area relative to the overall size of the can end. This enlarged tear strip is particularly useful, for example, in a typical 204 diameter can end that is most commonly used on beer cans of the type usually associated with a "six pack". The enlarged tear strip provides a larger opening through which the contents of the can may be rapidly dispensed. Because the enlarged openings can be more than thirty percent larger than conventional openings, the conventional conversion process by which a can end shell is converted into an easy open end is not satisfactory. In other words, enlarging the tear strip is not a matter of simply scaling up the dimensions of the conventional tear strip. Challenges exist in preventing "blow off" of the tear panel during opening and maintaining the smooth operation of the pull tab and resulting tear strip displacement.
It is an object of this invention to provide an improved converted can end with an enlarged opening through which the contents thereof are dispensed.
It is another object of the present invention to provide a method of further forming a can end so as to facilitate the rotation of the pull tab and operation of the easy open feature.
It is another object of this invention to provide a converted can end and a method for manufacturing the same.
It is still another object of this invention to provide the tooling stations for the formation of an improved converted can end.